The Royal Veterinary College at the University of London published a study in May concluding that owners of brachycephalic breeds may be putting their pets' welfare at stake because they consider these dogs' breathing difficulties to be normal.

"As a result of intense selection for short muzzles, 'brachycephalic' dogs, such as pugs, have a compressed upper jaw, which results in the soft tissue being crammed within the skull," the researchers reported. "These dogs are at high risk of developing brachycephalic obstructive airway syndrome (BOAS), with clinical signs including noisy and labored breathing, breathing difficulties even on short walks, overheating, gagging and choking."

The researchers surveyed the owners of 285 dogs, referred to the Queen Mother Hospital for Animals for all clinical services during a five-month period. Thirty-one dogs—including pugs, bulldogs, Pekingese, French bulldogs, Boston terriers and Cavalier King Charles spaniels—were affected by brachycephalic airway syndrome, and the researchers found that despite owners' reports of severe clinical signs in their pets, they did not perceive a "breathing problem."

All affected dogs' owners reported that their dogs snored (sometimes even when awake), compared with less than 2 percent of unaffected dogs, and two-thirds of affected dogs showed difficulty breathing during exercise. However, 58 percent of these dogs' owners said their pet did not have or have a history of breathing problems. This suggests that the majority of owners of dogs with brachycephalic airway syndrome don't recognize a problem and, therefore, don't seek veterinary assistance.

"Our study clearly shows that owners of brachycephalic dogs often dismiss the signs of this potentially severe breathing disorder as normal and are prepared to tolerate a high degree of respiratory compromise in their pets before seeking help," says the Royal Veterinary College's Rowena Packer, who carried out the research. "It may require a particularly acute attack, such as the dog losing consciousness, for owners to perceive a problem."

With brachycephalic breeds increasing in popularity—U.K. Kennel Club registrations of the pug alone increased from 3,500 to nearly 6,000 per year between 2007 and 2010—the authors urged owners of these dogs to seek care from a veterinarian if they notice any abnormal breathing sounds.